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Positron emission tomography/magnetic resonance (PET/MRI) hybrid imaging is now available for over a decade and although the quantity of installed systems is rather low, the number of emerging applications for cardiovascular diseases is still growing. PET/MRI provides integrated images of high quality anatomical and functional assessment obtained by MRI with the possibilities of PET for quantification of molecular parameters such as metabolism, inflammation, and perfusion. In recent years, sequential co-registration of myocardial tissue characterization with its molecular data had become an increasingly helpful tool in clinical practice and an integrated device simplifies this task. This review summarizes recent developments and future possibilities in the use of the PET/MRI in the diagnosis and treatment of cardiovascular disorders. [ABSTRACT FROM AUTHOR]

PET/MRI is a relevant application field for prostate cancer management, offering advantages in early diagnosis, staging, and therapy planning. Despite drawbacks such as higher costs, longer acquisition time, and the need for skilled personnel, the technical integration of PET and MRI provides valuable information for detecting primary tumors, identifying metastases, and characterizing the disease, leading to more accurate staging and personalized treatment strategies. However, PET/MRI adoption has been slow, but ongoing technological advancements and AI integration might overcome challenges and improve clinical utility. As precision medicine gains importance in oncology, PET/MRI's multiparametric data can tailor treatment plans to individual patients, providing a comprehensive assessment of tumor biology and aggressiveness for more effective therapeutic strategies. [ABSTRACT FROM AUTHOR]

Noninvasive imaging techniques, such as SPECT, PET, CT, echocardiography, or MRI, have become essential in cardiovascular research. They allow for the evaluation of biological processes in vivo without the need for invasive procedures. Nuclear imaging methods, such as SPECT and PET, offer numerous advantages, including high sensitivity, reliable quantification, and the potential for serial imaging. Modern SPECT and PET imaging systems, equipped with CT and MRI components in order to get access to morphological information with high spatial resolution, are capable of imaging a wide range of established and innovative agents in both preclinical and clinical settings. This review highlights the utility of SPECT and PET imaging as powerful tools for translational research in cardiology. By incorporating these techniques into a well-defined workflow- similar to those used in clinical imaging- the concept of "bench to bedside" can be effectively implemented. [ABSTRACT FROM AUTHOR]

We present guidelines by the European Association of Nuclear Medicine (EANM) for routine quality control (QC) of PET-CT and PET-MR systems. These guidelines are partially based on the current EANM guidelines for routine quality control of Nuclear Medicine instrumentation but focus more on the inherent multimodal aspect of the current, state-of-the-art PET-CT and PET-MR scanners. We briefly discuss the regulatory context put forward by the International Electrotechnical Commission (IEC) and European Commission (EC) and consider relevant guidelines and recommendations by other societies and professional organizations. As such, a comprehensive overview of recommended quality control procedures is provided to ensure the optimal operational status of a PET system, integrated with either a CT or MR system. In doing so, we also discuss the rationale of the different tests, advice on the frequency of each test and present the relevant MR and CT tests for an integrated system. In addition, we recommend a scheme of preventive actions to avoid QC tests from drifting out of the predefined range of acceptable performance values such that an optimal performance of the PET system is maintained for routine clinical use. [ABSTRACT FROM AUTHOR]

When this article was written, it coincided with the 11th anniversary of the installation of our PET/MR device in Munich. In fact, this was the first fully integrated device to be in clinical use. During this time, we have observed many interesting behaviors, to put it kindly. However, it is more critical that in this process, our understanding of the system also improved - including the advantages and limitations from a technical, logistical, and medical perspective. The last decade of PET/MRI research has certainly been characterized by most sites looking for a "key application." There were many ideas in this context and before and after the devices became available, some of which were based on the earlier work with integrating data from single devices. These involved validating classical PET methods with MRI (eg, perfusion or oncology diagnostics). More important, however, were the scenarios where intermodal synergies could be expected. In this review, we look back on this decade-long journey, at the challenges overcome and those still to come. [ABSTRACT FROM AUTHOR]

Background: In pulmonary arterial hypertension (PAH) increased afterload leads to adaptive processes of the right ventricle (RV) that help to maintain arterio-ventricular coupling of RV and preserve cardiac output, but with time the adaptive mechanisms fail. In this study, we propose a multimodal approach which allows to estimate prognostic value of RV coupling parameters in PAH patients. Methods: Twenty-seven stable PAH patients (49.5 ± 15.5 years) and 12 controls underwent cardiovascular magnetic resonance (CMR). CMR feature tracking analysis was performed for RV global longitudinal strain assessment (RV GLS). RV-arterial coupling was evaluated by combination of RV GLS and three proposed surrogates of RV afterload—pulmonary artery systolic pressure (PASP), pulmonary vascular resistance (PVR) and pulmonary artery compliance (PAC). 18-FDG positron emission tomography (PET) analysis was used to assess RV glucose uptake presented as SUVRV/LV. Follow-up time of this study was 25 months and the clinical end-point was defined as death or clinical deterioration. Results: Coupling parameters (RV GLS/PASP, RV GLS/PVR and RV GLS*PAC) significantly correlated with RV function and standardized uptake value (SUVRV/LV). Patients who experienced a clinical end-point (n = 18) had a significantly worse coupling parameters at the baseline visit. RV GLS/PASP had the highest area under curve in predicting a clinical end-point and patients with a value higher than (−)0.29%/mmHg had significantly worse prognosis. It was also a statistically significant predictor of clinical end-point in multivariate analysis (adjusted R2 = 0.68; p < 0.001). Conclusions: Coupling parameters are linked with RV hemodynamics and glucose metabolism in PAH. Combining CMR and hemodynamic measurements offers more comprehensive assessment of RV function required for prognostication of PAH patients. Trial Registration: NCT03688698, 09/26/2018, retrospectively registered; Protocol ID: 2017/25/N/NZ5/02689 [ABSTRACT FROM AUTHOR]

• EU Directive 2013/59/Euratom requires optimisation of radiotherapy with dosimetry. • EFOMP's policy is to promote medical physics in molecular radiotherapy. • EFOMP presents recommendations to implement patient-specific dosimetry. The European Council Directive 2013/59/Euratom (BSS Directive) includes optimisation of treatment with radiotherapeutic procedures based on patient dosimetry and verification of the absorbed doses delivered. The present policy statement summarises aspects of three directives relating to the therapeutic use of radiopharmaceuticals and medical devices, and outlines the steps needed for implementation of patient dosimetry for radioactive drugs. To support the transition from administrations of fixed activities to personalised treatments based on patient-specific dosimetry, EFOMP presents a number of recommendations including: increased networking between centres and disciplines to support data collection and development of codes-of-practice; resourcing to support an infrastructure that permits routine patient dosimetry; research funding to support investigation into individualised treatments; inter-disciplinary training and education programmes; and support for investigator led clinical trials. Close collaborations between the medical physicist and responsible practitioner are encouraged to develop a similar pathway as is routine for external beam radiotherapy and brachytherapy. EFOMP's policy is to promote the roles and responsibilities of medical physics throughout Europe in the development of molecular radiotherapy to ensure patient benefit. As the BSS directive is adopted throughout Europe, unprecedented opportunities arise to develop informed treatments that will mitigate the risks of under- or over-treatments. [ABSTRACT FROM AUTHOR]

• We present a CS-accelerated radial MS-CAIPIRINHA technique for first-pass myocardial MRI on integrated PET/MR systems. • The new technique allows MRI perfusion assessment with an extended anatomical coverage (six slices per RR interval). • Joint diagnosis with the simultaneously acquired three-dimensional PET benefits from an adequate coverage on the MRI-side. Simultaneous acquisition of myocardial first-pass perfusion MRI and 18F-FDG PET viability imaging on integrated whole-body PET/MR hybrid systems synergistically delivers both functional and metabolic information on the tissue state. While PET viability scans are inherently three-dimensional, conventional MR myocardial perfusion imaging is typically performed using only three short-axis slices with a temporal resolution of one RR-interval. To improve the integrated diagnostics, an acquisition and image reconstruction method based on "Multi-Slice Controlled Aliasing In Parallel Imaging Results IN Higher Acceleration (MS-CAIPIRINHA)" was developed extending anatomical coverage for MR perfusion imaging to six short-axis slices per RR-interval. An ECG-gated radial TurboFLASH MR pulse sequence with dual band excitation was implemented on an integrated whole-body PET/MR system and a model-based reconstruction technique was developed to fully reconstruct the undersampled CAIPIRINHA acquisitions. An 18F-FDG viability PET scan was performed simultaneously to the MR protocol, additionally complemented by a late enhancement MRI acquisition (LGE). The developed imaging technique was tested in five patients with known collateralized coronary total occlusions, resulting in improved characterization of perfusion across areas of decreased tissue viability as indicated by the simultaneously determined 18F-FDG uptake. While conventional MR perfusion with only three slice positions was occasionally missing substantial parts of the viable area, the new approach achieved LV coverage only slightly inferior to LGE imaging and therefore better comparable to PET results. The quality of first-pass enhancement curves was comparable between conventional and radial MS-CAIPIRINHA-based acquisitions. [ABSTRACT FROM AUTHOR]

Hybrid imaging devices including PET/CT and SPECT/CT have seen a great success in clinical routine, especially in the field of oncology. With the recent advent of PET/MRI scanners, expectations that PET/MRI would replicate that success were accordingly high. The combination of molecular imaging with a variety of very specific PET tracers and the high spatial resolution of MRI are expected to result in increased diagnostic accuracy or even in the creation of additional demands for hybrid imaging. However, as these systems have entered the market just recently, experience in the field of nuclear cardiology is limited and some applications still need to be validated. Owing to the profound technical differences between CT and MRI, which influences not only the estimation of the photon attenuation but also causes marked differences in the workflow, particularly in cardiovascular studies (such as the need for special personnel training and interaction between nuclear medicine specialists, radiologists, and physicists), the “familiarization phase” with this new technique also seems to be extended. However, the approach to study various conditions such as perfusion, viability, and atherosclerosis in a single imaging examination session using PET and MRI offers advantages. Although MRI allows for a detailed morphologic characterization of the studied tissue, PET adds the information on functional biological markers that are not (or at least not fully) measurable by MRI. Thus, this combined imaging approach will prove valuable in distinct cardiac diseases (such as myocarditis and cardiac sarcoidosis) and will offer vast research opportunities. [ABSTRACT FROM AUTHOR]

Objectives The purpose of this study was to compare myocardial blood flow (MBF) and myocardial flow reserve (MFR) estimates from rubidium-82 positron emission tomography ( 82 Rb PET) data using 10 software packages (SPs) based on 8 tracer kinetic models. Background It is unknown how MBF and MFR values from existing SPs agree for 82 Rb PET. Methods Rest and stress 82 Rb PET scans of 48 patients with suspected or known coronary artery disease were analyzed in 10 centers. Each center used 1 of 10 SPs to analyze global and regional MBF using the different kinetic models implemented. Values were considered to agree if they simultaneously had an intraclass correlation coefficient >0.75 and a difference <20% of the median across all programs. Results The most common model evaluated was the Ottawa Heart Institute 1-tissue compartment model (OHI-1-TCM). MBF values from 7 of 8 SPs implementing this model agreed best. Values from 2 other models (alternative 1-TCM and Axially distributed) also agreed well, with occasional differences. The MBF results from other models (e.g., 2-TCM and retention) were less in agreement with values from OHI-1-TCM. Conclusions SPs using the most common kinetic model—OHI-1-TCM—provided consistent results in measuring global and regional MBF values, suggesting that they may be used interchangeably to process data acquired with a common imaging protocol. [ABSTRACT FROM AUTHOR]

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Myocardial perfusion imaging (MPI) with thallium 201 (201Tl) or 99mTc based imaging agents has become a major tool for noninvasive identification of coronary artery disease (CAD). However, single photon emission computed tomography (SPECT) imaging with the current agents is vulnerable to artifacts associated with soft tissue attenuation, proximal gastrointestinal activity, image quality, and suboptimal sensitivity and is limited by the degree of first-pass myocardial extraction. The development of 18F-based flurpiridaz F-18 takes advantage of positron emission tomography (PET) to overcome many of the imaging issues and structural design to achieve an ideal MPI agent profile. Flurpiridaz F-18 was designed to bind to mitochondrial complex I with high affinity and demonstrates high heart uptake in multiple species with clear delineation of perfusion deficits. It exhibits rapid uptake in the myocardium, prolonged retention, and superior extraction versus flow profiles compared with 201Tl and 99mTc-sestamibi. A first in man study has established the safety and dosimetry of flurpiridaz F-18 and confirmed high sustained cardiac uptake. Subsequent studies performed in CAD patients established the dose and timing needed to detect perfusion deficits when the agent is administered under rest and stress conditions. This review compares the current preclinical and clinical data with an ideal MPI agent profile. The assessment indicates flurpiridaz F-18 represents a new generation of PET MPI agents and demonstrates significantly improved molecular and imaging characteristics. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this research was to evaluate kinetics and extent of myocardial contrast enhancement (CE) in comparison with single-photon emission computed tomography (SPECT) early after acute myocardial infarction (AMI). Background: Quantification of infarct size serves as a surrogate end point in evaluating new therapies of AMI. Contrast-enhanced magnetic resonance imaging (CeMRI) of the myocardium is a promising new method for identification of irreversible tissue injury. Methods: A total of 33 patients were examined by CeMRI and SPECT 7 ± 2 days after AMI and successful coronary intervention. After gadolinium-diethylenetraimine pentaacetic acid injection (0.2 mmol/kg), continuous short-axis slices of the left ventricle (LV) were acquired every 7 min up to 42 min using different inversion times (TI). Myocardial CE at each imaging time point was quantified and compared with corresponding SPECT perfusion defect. Results: All patients showed myocardial CE in the infarct region. A constant TI for CeMRI resulted in a decrease of signal intensity and extent of CE on late acquisitions. With TI adjustment, infarct image intensity peaked at 21 min with a contrast of 478% of remote myocardium and remained at this level up to 42 min after contrast injection (437%); CE extent was stable over time and agreed well with SPECT within an average difference of 3% of the LV myocardium, yielding the best correlation at 28 min (r = 0.86). Conclusions: In patients after AMI and successful reperfusion, CE is stable over time and matches well with SPECT perfusion defect; CeMRI under standardized conditions can accurately assess myocardial infarct size in vivo and may be attractive for serving as a surrogate end point early after AMI. [Copyright &y& Elsevier]

: ObjectivesThe study compared flow reserve indices by magnetic resonance imaging (MRI) with quantitative measures of coronary angiography and positron emission tomography (PET).: BackgroundThe noninvasive evaluation of myocardial flow by MRI has recently been introduced. However, a comparison to quantitative flow measurement as assessed by PET has not been reported in patients with coronary artery disease (CAD).: MethodsTwo groups of healthy volunteers and 25 patients with angiographically documented CAD were examined by MRI and PET at rest and during adenosine stress. Dynamic MRI was performed using a multi-slice ultra-fast hybrid sequence and a rapid gadolinium-diethylenetriaminepenta-acetic acid bolus injection (0.05 mmol/l). Upslope and peak-intensity indices were regionally determined from first-pass signal intensity curves and compared to N-13 ammonia PET flow reserve measurements.: ResultsIn healthy volunteers, the upslope analysis showed a stress/rest index of 2.1 ± 0.6, which was higher than peak intensity (1.5 ± 0.3), but lower than flow reserve by PET (3.9 ± 1.1). Localization of coronary artery stenoses (>75%, MRI <1.2), based on the upslope index, yielded sensitivity, specificity and diagnostic accuracy of 69%, 89% and 79%, respectively. Upslope index correlated with PET flow reserve (r = 0.70). A reduced coronary flow reserve (PET <2.0, MRI <1.3) was detected by the upslope index with sensitivity, specificity and diagnostic accuracy of 86%, 84% and 85%, respectively.: ConclusionsMagnetic resonance imaging first-pass perfusion measurements underestimate flow reserve values, but may represent a promising semi-quantitative technique for detection and severity assessment of regional CAD. [Copyright &y& Elsevier]

Background: Characterization of tissue integrity and inflammatory processes after acute myocardial infarction (AMI) using non-invasive imaging is predictive of patient outcome. Quantitative cardiovascular magnetic resonance (CMR) techniques such as native T1 and extracellular volume (ECV) mapping as well as 18F-FDG positron emission tomography (PET) imaging targeting inflammatory cell populations are gaining acceptance, but are often applied without assessing their quantitative potential. Using simultaneously acquired PET/CMR data from patients early after AMI, this study quantitatively compares these three imaging markers and investigates links to blood markers of myocardial injury and systemic inflammatory activity. Methods: A total of 25 patients without microvascular obstruction were retrospectively recruited. All imaging was simultaneously performed 5 ± 1 days after revascularization following AMI on an integrated 3T PET/MRI scanner. Native and post-contrast T1 data were acquired using a modified Look-Locker inversion recovery (MOLLI) sequence, ECV maps were calculated using individually sampled hematocrit. 18F-FDG PET was executed after 1 day of dietary preparation, 12 h of fasting, and administration of heparin. ECV, 18F-FDG and native T1 data were compared mutually as well as to peak counts of peripheral blood markers (creatine kinase, creatine kinase-MB, troponin, leukocytes, monocytes) and infarct size. Results: High intra-patient correlations of relative ECV, 18F-FDG PET and native T1 signal increases were observed in combination with no inter-patient correlation of maximum absolute values at the infarct center, suggesting well-colocalized but physiologically diverse processes begetting the respective image signals. Comparison of maximum image signals to markers of myocardial damage and systemic inflammation yielded highly significant correlations of ECV to peak creatine kinase-MB and overall infarct size as well as between native T1 and peak monocyte counts. Conclusions: Absolute native T1 values at the infarct core early after AMI can be linked to the systemic inflammatory response independent of infarct size. Absolute ECV at the infarct core is related to both infarct size and blood markers of myocardial damage. [ABSTRACT FROM AUTHOR]

Abstract: This review will focus on the clinical potential of PET/CT for the characterization of cardiovascular diseases. We describe the technical challenges of combining instrumentation with very different imaging performance and discuss the clinical applications in the field of cardiology. [Copyright &y& Elsevier]

Objectives: We sought to investigate the usefulness of integrated positron emission tomography (PET) and computed tomography (CT) for in vivo characterization of an angiogenesis-directed molecular intervention. Background: Controversies about the effectiveness of molecular therapies for cardiovascular disease have prompted the need for more powerful noninvasive imaging techniques. Methods: In a model of regional adenoviral transfer of the VEGF121 gene to myocardium of healthy pigs, PET-CT using multiple molecular-directed radiotracers was employed. Results: Two days after gene transfer, successful transgene expression was noninvasively confirmed by a reporter probe targeting co-expressed HSV1-sr39tk reporter gene. The CT-derived ventricular function and morphology remained unaltered (left ventricular ejection fraction 57 ± 5% in adenovirus-injected animals vs. 53 ± 5% in controls; p = 0.36). Increased regional perfusion was identified in areas overexpressing VEGF (myocardial blood flow during adenosine-induced vasodilation 1.47 ± 0.49 vs. 1.14 ± 0.27 ml/g/min in remote areas; p = 0.01), corroborating in vivo effects on microvascular tone and permeability. Finally, regional angiogenesis-associated αvβ3 integrin expression was not enhanced, suggesting little contribution to the perfusion increase. Fusion of CT morphology and tracer-derived molecular signals allowed for accurate regional localization of biologic signals. Findings were validated by control vectors, sham-operated animals, and ex vivo tissue analysis. Conclusions: Integrated PET-CT has the potential to dissect cardiovascular biologic mechanisms from gene expression to physiologic function and morphology. The VEGF overexpression in healthy myocardium increases myocardial perfusion without significant up-regulation of αvβ3 integrin adhesion molecules early after the intervention. [Copyright &y& Elsevier]

The local inflammatory response following acute myocardial infarction (AMI) is increasingly being recognized as a central factor determining infarct healing. Myocardial inflammation can be visualized in patients using fasting 18F-FDG PET/MRI. Although this novel biosignal correlates with long-term functional outcome, the corresponding cellular substrate is not well understood. Here we present a retrospective analysis of 29 patients with AMI who underwent revascularization, suggesting a connection between post infarction myocardial fasting 18F-FDG uptake, monocyte platelet aggregates (MPA), and P2Y 12 inhibition. In detail, patients with high MPA percentages of CD14highCD16+ and CD14lowCD16+ monocytes had significantly higher local 18F-FDG uptake (SUV mean) in the infarcted myocardium than patients with low MPA (p < 0.05). Furthermore, there was an association of high MPA percentage in all monocyte subpopulations with deteriorating ΔLV-EF after 6 months (p < 0.01), which was confirmed in an extended analysis with additional 29 patients without PET/MRI data available. In this analysis, administration of Ticagrelor was associated with lower MPA percentage of CD14high monocyte subpopulations than Clopidogrel (p < 0.01) or Prasugrel (p < 0.05). Taken together, the findings from this analysis suggest that platelet aggregability may affect monocyte extravasation into the infarcted myocardium and influence long-term functional outcome. P2Y 12 inhibition may intervene in this pathophysiologic process. Prospective studies are needed to further examine this important relationship. • High relative levels of monocyte-platelet aggregates are associated with strong myocardial inflammation in patients with AMI. • P2Y12 inhibitor choice may affect MPA formation, with ticagrelor showing the lowest relative MPA levels. • The relationship between platelet inhibition, myocardial inflammation, and cardiac remodeling may represent an axis of therapeutic relevance. [ABSTRACT FROM AUTHOR]

Abstract: An important evolution has taken place recently in the field of cardiovascular Positron Emission Tomography (PET) imaging. Being originally a highly versatile research tool that has contributed significantly to advance our understanding of cardiovascular physiology and pathophysiology, PET has gradually been incorporated into the clinical cardiac imaging portfolio contributing to diagnosis and management of patients investigated for coronary artery disease (CAD). PET myocardial perfusion imaging (MPI) has an average sensitivity and specificity around 90% for the detection of angiographically significant CAD and it is also a very accurate technique for prognostication of patients with suspected or known CAD. In clinical practice, Rubidium-82 (82Rb) is the most widely used radiopharmaceutical for MPI that affords also accurate and reproducible quantification in absolute terms (ml/min/g) comparable to that obtained by cyclotron produced tracers such as Nitrogen-13 ammonia (13N-ammonia) and Oxygen-15 labeled water (15O-water). Quantification increases sensitivity for detection of multivessel CAD and it may also be helpful for detection of early stages of atherosclerosis or microvascular dysfunction. PET imaging combining perfusion with myocardial metabolism using 18F-Fluorodeoxyglucose (18F FDG), a glucose analog, is an accurate standard for assessment of myocardial hibernation and risk stratification of patients with left ventricular dysfunction of ischemic etiology. It is helpful for guiding management decisions regarding revascularization or medical treatment and predicting improvement of symptoms, exercise capacity and quality of life post-revascularization. The strengths of PET can be increased further with the introduction of hybrid scanners, which combine PET with computed tomography (PET/CT) or with magnetic resonance imaging (PET/MRI) offering integrated morphological, biological and physiological information and hence, comprehensive evaluation of the consequences of atherosclerosis in the coronary arteries and the myocardium. [Copyright &y& Elsevier]

Abstract: Purpose: To simulate and optimize a MR protocol for squamous cell cancer of the head and neck (HNSCC) patients for potential future use in an integrated whole-body MR–PET scanner. Materials and methods: On a clinical 3T scanner, which is the basis for a recently introduced fully integrated whole-body MR–PET, 20 patients with untreated HNSCC routinely staged with 18F-FDG PET/CT underwent a dedicated MR protocol for the neck. Moreover, a whole-body Dixon MR-sequence was applied, which is used for attenuation correction on a recently introduced hybrid MR–PET scanner. In a subset of patients volume-interpolated-breathhold (VIBE) T1w-sequences for lungs and liver were added. Total imaging time was analyzed for both groups. The quality of the delineation of the primary tumor (scale 0–3) and the presence or absence of lymph node metastases (scale 1–5) was evaluated for CT, MR, PET/CT and a combination of MR and PET to ensure that the MR–PET fusion does not cause a loss of diagnostic capability. PET was used to identify distant metastases. The PET dataset for simulated MR/PET was based on a segmentation of the CT data into 4 classes according to the approach of the Dixon MR-sequence for MR–PET. Standard of reference was histopathology in 19 cases. In one case no histopathological confirmation of a primary tumor could be achieved. Results: Mean imaging time was 35:17min (range: 31:08–42:42min) for the protocol including sequences for local staging and attenuation correction and 44:17min (range: 35:44–54:58) for the extended protocol. Although not statistically significant a combination of MR and PET performed better in the delineation of the primary tumor (mean 2.20) compared to CT (mean 1.40), MR (1.95) and PET/CT (2.15) especially in patients with dental implants. PET/CT and combining MR and PET performed slightly better than CT and MR for the assessment of lymph node metastases. Two patients with distant metastases were only identified by PET. Conclusion: We established a potential MR-protocol to be used for HNSCC patients in a recently introduced MR–PET scanner. The proposed protocol can be performed in an acceptable time frame and did not lead to a loss of diagnostic capability compared to PET/CT. [Copyright &y& Elsevier]

Objectives: The aim of this study was to characterize the relationship between impaired sympathetic innervation and arrhythmia with noninvasive biologic imaging in an animal model of post-infarct ventricular tachycardia (VT). Background: Innervation might be abnormal in the normally perfused borderzone of myocardial infarction, contributing to myocardial catecholamine overexposure and arrhythmogenic risk. Methods: Myocardial infarction was induced by mid-left anterior descending coronary artery balloon occlusion in 11 pigs. Positron emission tomography (PET) of tissue perfusion and catecholamine uptake and storage was performed with [13N]-ammonia and [11C]-epinephrine 4 to 12 weeks later. Magnetic resonance imaging and invasive electrophysiology (electroanatomic mapping, basket catheter, VT inducibility) were performed within 1 week of PET. Results: When compared with a normal database of 9 healthy animals, reduced perfusion was observed in 37 ± 7% of the left ventricle (LV). Epinephrine retention was reduced in 44 ± 7% of LV, resulting in a perfusion/innervation mismatch of 7 ± 4% LV. Sustained monomorphic VT was inducible in 7 of 11 animals. These animals showed a larger perfusion/innervation mismatch (10 ± 4% vs. 4 ± 2% LV for animals without VT; p = 0.02). Regionally, the degree of perfusion/innervation mismatch did not correlate with wall thickness or thickening but showed a significant correlation with reduced myocardial voltage (r = 0.93; p = 0.001) and with the site of earliest VT activation (chi-square 13.1; p < 0.001). Conclusions: Noninvasive mapping of cardiac sympathetic nerve terminals reveals regionally impaired catecholamine uptake and storage in the normally perfused borderzone after experimental myocardial infarction. These areas might be useful to characterize the individual risk for ventricular arrhythmia. [Copyright &y& Elsevier]

Objectives: This study sought to evaluate the diagnostic value of contrast-enhanced magnetic resonance imaging (CMR) and single-photon emission computed tomography (SPECT) for detection of myocardial necrosis after acute myocardial infarction (AMI). Background: Single-photon emission computed tomography is widely accepted in the clinical setting for detection and estimation of myocardial infarction. Contrast-enhanced magnetic resonance imaging offers technical advantages and is therefore a promising new method for identification of infarcted tissue. Methods: Seventy-eight patients with AMI were examined by CMR and SPECT 7 days after percutaneous coronary intervention. Contrast-enhanced magnetic resonance imaging and SPECT images were scored for presence and location of infarction using a 17-segment model. Results were compared with the peak troponin T level, electrocardiographic, and angiographic findings. Results: Acute myocardial infarction was detected significantly more often by CMR than SPECT (overall sensitivity: 97% vs. 87%; p = 0.008). Sensitivity of CMR was superior to SPECT in detecting small infarction as assessed by the peak troponin T level <3.0 ng/ml (92 vs. 69%; p = 0.03), and infarction in non-anterior location (98% vs. 84%; p = 0.03). Non–Q-wave infarctions were more likely to be detected by CMR (sensitivity 85% vs. 46%; p = 0.06). While CMR offered high sensitivity for detection of AMI irrespective of the infarct-related artery, SPECT was less sensitive, particularly within the left circumflex artery territory. Conclusions: Contrast-enhanced magnetic resonance imaging is superior to SPECT in detecting myocardial necrosis after reperfused AMI because CMR detects small infarcts that were missed by SPECT independent of the infarct location. Thus, CMR is attractive for accurate detection and assessment of the myocardial infarct region in patients early after AMI. [Copyright &y& Elsevier]

We investigated whether N-terminal pro-brain natriuretic peptide (NT–pro-BNP) that was measured on admission in patients with acute myocardial infarction (AMI) predicts the efficacy of reperfusion or whether NT–pro-BNP provides prognostic information independent of infarct size as estimated by single-photon emission computed tomographic scintigraphy. The study included 174 patients with ST-segment elevation AMI who were admitted within 24 hours of pain onset. NT–pro-BNP level was measured on admission. Paired scintigraphic studies (before and 7 to 14 days after reperfusion) were performed to assess infarct size and define myocardial salvage. One-year clinical follow-up was assessed. Patients were categorized into the high NT–pro-BNP group (57 patients in the upper tertile of NT–pro-BNP) and low NT–pro-BNP group (117 patients in the middle and lower tertiles of NT–pro-BNP). Initial median perfusion defect was 35.0% (interquartile rage 20.0 to 53.0%) of the left ventricle in the high NT–pro-BNP group versus 19.0% (interquartile range 10.0 to 32.2) of the left ventricle in the low NT–pro-BNP group (p <0.001). Median salvage index was 0.36 (interquartile range 0.16 to 0.86) in the high NT–pro-BNP group versus 0.53 (interquartile range 0.31 to 0.75) in the low NT–pro-BNP group (p = 0.22). After adjustment in Cox’s proportional hazards model, NT–pro-BNP remained an independent correlate of 1-year mortality (adjusted hazard ratio 2.31, 95% confidence interval 1.09 to 4.89, p = 0.03, high vs low NT–pro-BNP group). In conclusion, NT–pro-BNP measured on admission in patients with AMI correlates with scintigraphic area at risk and predicts prognosis but does not predict the efficacy of mechanical reperfusion by stenting or angioplasty. [Copyright &y& Elsevier]

Objectives: The aim of this study was to investigate whether there are gender-associated differences in the amount of myocardial salvage after primary percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI). Background: Despite having a more adverse cardiovascular risk profile, women with AMI have similar or even better outcomes after primary PCI compared with men. The reasons for these findings are unclear. Methods: In this study we included 202 women and 561 men with AMI who underwent primary PCI in the setting of three randomized trials. The primary end point of the study was myocardial salvage index (proportion of initial perfusion defect salvaged by reperfusion therapy), obtained by paired scintigraphic studies performed 7 to 10 days apart. Results: The amount of myocardium at risk or initial perfusion defect (median [25th, 75th percentiles]) did not differ significantly between women and men (22.0% [12.0, 40.0] vs. 24.0% [14.0, 39.0] of the left ventricle [LV], p = 0.26). Final infarct size, measured in the follow-up scintigraphy, was significantly smaller in women than in men (6.0% [0.71, 18.7] vs. 10.0% [3.9, 21.8] of the LV, p = 0.001). Myocardial salvage index was 0.64 (0.35, 0.95) in women versus 0.50 (0.26, 0.77) in men (p < 0.001). After adjustment for baseline characteristics, female gender was an independent predictor of greater myocardial salvage after PCI (p = 0.002). Conclusions: The efficacy of primary PCI in patients with AMI appears to be gender-dependent. Myocardial salvage achieved by primary PCI is greater in women than in men. [Copyright &y& Elsevier]

Objectives: The aim of this research was to evaluate kinetics and extent of myocardial contrast enhancement (CE) in comparison with single-photon emission computed tomography (SPECT) early after acute myocardial infarction (AMI). Background: Quantification of infarct size serves as a surrogate end point in evaluating new therapies of AMI. Contrast-enhanced magnetic resonance imaging (CeMRI) of the myocardium is a promising new method for identification of irreversible tissue injury. Methods: A total of 33 patients were examined by CeMRI and SPECT 7 +/- 2 days after AMI and successful coronary intervention. After gadolinium-diethylenetraimine pentaacetic acid injection (0.2 mmol/kg), continuous short-axis slices of the left ventricle (LV) were acquired every 7 min up to 42 min using different inversion times (TI). Myocardial CE at each imaging time point was quantified and compared with corresponding SPECT perfusion defect. Results: All patients showed myocardial CE in the infarct region. A constant TI for CeMRI resulted in a decrease of signal intensity and extent of CE on late acquisitions. With TI adjustment, infarct image intensity peaked at 21 min with a contrast of 478% of remote myocardium and remained at this level up to 42 min after contrast injection (437%); CE extent was stable over time and agreed well with SPECT within an average difference of 3% of the LV myocardium, yielding the best correlation at 28 min (r = 0.86). Conclusions: In patients after AMI and successful reperfusion, CE is stable over time and matches well with SPECT perfusion defect; CeMRI under standardized conditions can accurately assess myocardial infarct size in vivo and may be attractive for serving as a surrogate end point early after AMI. [ABSTRACT FROM AUTHOR]

: ObjectivesThe effects of long-term cardiac resynchronization therapy (CRT) on left ventricular (LV) energetics and metabolic reserve were evaluated.: BackgroundCardiac resynchronization therapy is a new therapy for patients with drug-refractory severe heart failure (HF).: MethodsTen patients with idiopathic dilated cardiomyopathy who had undergone implantation of biventricular pacemaker 8 ± 5 months earlier were studied during two conditions: CRT switched on, and after CRT was switched off for 24 h. Left ventricular function was measured using echocardiography and oxidative metabolism using [11C]acetate positron emission tomography. Both measurements were performed at rest and during dobutamine-induced stress (5 μg/kg/min). Basal- and adenosine-stimulated (140 μg/kg/min) myocardial blood flow were quantitated using [15O]water.: ResultsDuring CRT off, LV stroke volume was significantly reduced at rest (72 ± 18 ml vs. 63 ± 15 ml, p < 0.05), but LV oxidative metabolism (Kmono) remained unchanged (0.046 ± 0.008 vs. 0.054 ± 0.016 min−1) leading to a significant deterioration of myocardial efficiency of forward work (from 48.2 ± 16.7 to 36.6 ± 11.7 mm Hg·l/g, p < 0.05). During dobutamine-induced stress, stroke volume and Kmono values were not different whether CRT was on or off. However, myocardial efficiency (56.1 ± 16.1 vs. 49.8 ± 18.0 mm Hg·ml·g−1·min−1, p = 0.099) and metabolic reserve, the response of Kmono to dobutamine (0.023 ± 0.014 vs. 0.013 ± 0.014 min−1, p = 0.09), tended to reduce when CRT was switched off. Cardiac resynchronization therapy had no effects on myocardial perfusion. Natriuretic peptides increased significantly during CRT-off period.: ConclusionsLong-term CRT has beneficial effects on LV function and myocardial efficiency at rest in patients with HF. These effects are not associated with changes in myocardial perfusion or oxygen consumption. During dobutamine-induced stress, CRT does not affect functional parameters, but myocardial efficiency and metabolic reserve may be increased. [Copyright &y& Elsevier]